U.S. Pat. No. 4,109,318 to Hutchins discloses an inline blender having propellor-like blades of graduated configuration placed along a central shaft of a flow conduit. The blades form continuous spiral mixing channels which extend well into the center of the conduit. U.S. Pat. No. 4,123,178 to Salzman et al discloses a similar inline blender. In each of the above patents a number of propellor-like blades are mounted on a central shaft to impart a general swirl-type motion to a liquid travelling therethrough. Reversal of the direction of swirl is recognized as a mixing expedient. Numerous other static devices, usually mixers, are disclosed in the art as contributing some desirable property to a liquid flowing therethrough. See for example, U.S. Pat. Nos. 4,441,823; 3,582,048; 4,427,030 and the like.
Also, in prior art, but not heretofore related to static mixers, is U.S. Pat. No. 4,479,805 to Batra which disclosed the pumping of an asphaltene-bearing oil through a perforated pipe to reduce the particle size to asphaltene particularly when the asphaltene was carried in water-oil emulsions. Notwithstanding the process of Batra, it was found that the variety of asphaltene in oil and made still further improvements in asphaltene conditioning desirable in order to reduce the particulate emissions from stack gas.
An additional aspect of the commercial background of the invention is the fact that heavy fuel oils have had varying increasing amounts of asphaltene therein and the quantity of quality of asphaltene can vary considerably shipment-to-shipment.